Abstract: Power electronics is an area that concerns the applications of electronic principle into situations where the power level is controlled than signal level. Semiconductor power switches such as thyristors, GTOs, MOSEFTS, etc. works on the principal of power electronics. The industrial applications demands the inventions in converter, Pulse width modulation techniques, control and estimations, DSP, ASICs, etc. which also needs contribution of power control operations. This paper provides brief summary of power control device i.e. thyristor working in different modes of operations. Applications of thyristor using different modes to control the speed of motor are also summarized at glance.

Keywords: ASIC, SCRs, IGBT, cycloconverter, chopper, 8255 PPI.